Impact of insecticides on the structure and productivity of insect pest and natural enemy communities associated with intercropping in cotton agroecosystems

Abstract

Effects of insecticides on the structure and productivity of insect pest and natural enemy communities were analyzed in the four types of cotton agroecosystem associated with intercropping in Raoyang County, HeBei Province, China. The interaction of chemical control × intercropping had a significant effect on the most community structure parameters of insect pest and natural enemy communities, except for the diversity index of the predator community. The damage index for the insect pest community and control index of the natural enemy community were also affected significantly by the chemical control × intercropping interaction. Pearson correlation analyzes showed that community structure and productivity of insect pest and predator communities had a complex relationship with lower trophic productivity in these cotton agroecosystems. Few effects of chemical control on these correlations were found. Chemical methods influenced the correlations between insect pest community productivity and parasitoid community structure in most cotton agroecosystems. Our results suggest that the interaction of chemical control × intercropping significantly influenced the damage index, the control index, and the correlation between community structure and productivity of insect pest and natural enemy communities in cotton agroecosystems.